KR101789913B1 - Power conversion device for preventing a circulating current and method of driving the same - Google Patents
Power conversion device for preventing a circulating current and method of driving the same Download PDFInfo
- Publication number
- KR101789913B1 KR101789913B1 KR1020160017100A KR20160017100A KR101789913B1 KR 101789913 B1 KR101789913 B1 KR 101789913B1 KR 1020160017100 A KR1020160017100 A KR 1020160017100A KR 20160017100 A KR20160017100 A KR 20160017100A KR 101789913 B1 KR101789913 B1 KR 101789913B1
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- Prior art keywords
- inverter
- controller
- output
- proportional
- compensation
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Classifications
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
- H02M7/42—Conversion of dc power input into ac power output without possibility of reversal
- H02M7/44—Conversion of dc power input into ac power output without possibility of reversal by static converters
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M1/00—Details of apparatus for conversion
- H02M1/08—Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters
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- H02M2007/4822—
Abstract
A power conversion apparatus and a driving method thereof for preventing a circulating current are disclosed. The power conversion apparatus includes a first inverter and a second inverter connected in parallel, a first operation controller for controlling operation of the first inverter, and a second operation controller for controlling operation of the second inverter. At least one of the first operation control unit and the second operation control unit includes a circulation current control unit that suppresses a circulation current that may be generated between the inverters.
Description
BACKGROUND OF THE
The power conversion apparatus is an apparatus for converting power, and mainly uses an inverter. Such a power conversion apparatus may be implemented using one inverter, but may be implemented using a plurality of inverters connected in parallel for a large capacity system as shown in FIG.
1 is a view showing a conventional power conversion apparatus.
Referring to FIG. 1, a power conversion apparatus may include
Inverter 1 100 outputs three-phase output currents I u1 , I v1 and I w1 and inverter 2 102 also outputs three-phase output currents I u2 , I v2 and I w2 .
However, since the
However, the conventional power conversion apparatus does not include a function capable of suppressing such a circulating current.
SUMMARY OF THE INVENTION The present invention provides a power conversion apparatus and a driving method thereof for preventing a circulating current.
In order to achieve the above object, a power conversion apparatus according to an embodiment of the present invention includes a first inverter and a second inverter connected in parallel, a first operation controller for controlling operation of the first inverter, And a second operation control unit for controlling the operation of the two inverters. At least one of the first operation control unit and the second operation control unit includes a circulation current control unit that suppresses a circulation current that may be generated between the inverters.
According to another aspect of the present invention, there is provided a power conversion apparatus comprising: a first inverter and a second inverter connected in parallel; An inverter control unit for controlling operations of the switches of the second inverter; And a compensation unit for compensating an output of the inverter control unit to adjust a duty ratio of the switches.
According to an aspect of the present invention, there is provided a method of driving a power conversion device including: detecting output currents of a second inverter connected in parallel with a first inverter; Checking the value of the circulating current through the sum of the detected output currents; And compensating a control value for controlling the switches in the second inverter according to the value of the determined circulation current to suppress the circulation current.
The power conversion device according to the present invention suppresses the circulating current between the inverters connected in parallel, so that the total energy conversion efficiency of the power conversion device can be improved and the quality of the output current can be improved.
1 is a view showing a conventional power conversion apparatus.
2 is a circuit diagram schematically showing the structure of a power conversion apparatus according to an embodiment of the present invention.
Fig. 3 is a circuit diagram showing a detailed structure of the power converter of Fig. 2; Fig.
4 is a diagram illustrating an operation control unit according to an embodiment of the present invention.
As used herein, the singular forms "a", "an" and "the" include plural referents unless the context clearly dictates otherwise. In this specification, the terms "comprising ", or" comprising "and the like should not be construed as necessarily including the various elements or steps described in the specification, Or may be further comprised of additional components or steps. Also, the terms "part," " module, "and the like described in the specification mean units for processing at least one function or operation, which may be implemented in hardware or software or a combination of hardware and software .
The present invention relates to a power conversion apparatus including inverters connected in parallel and a driving method thereof, and proposes a technique for preventing a circulating current that may be generated between inverters due to the parallel structure of inverters.
The power conversion apparatus of the present invention can be used in a wide range of fields such as an AC / DC modular inverter for renewable energy, a solar power generation system, a wind power generation system, an energy storage system, an uninterruptible power supply system, a reactive power compensation system, .
According to one embodiment, the power conversion apparatus of the present invention can prevent the generation of the circulating current by controlling the inverter so that the sum of the three-phase output currents output from one inverter becomes zero. For example, the power conversion apparatus may control the duty ratio of the switches of the inverter to reduce the sum of the three-phase output currents output from the inverter to zero to suppress the circulation current.
Hereinafter, various embodiments of the present invention will be described in detail with reference to the accompanying drawings.
2 is a circuit diagram schematically showing the structure of a power conversion apparatus according to an embodiment of the present invention. In FIG. 2, although two inverters are connected in parallel for convenience of explanation, the power converter may include three or more inverters.
2, the power conversion apparatus of the present embodiment may include a plurality of DC /
Each of the
The
These
The
The first
The
The second
Becomes the output current output from the inverter (200 and 202) (I u1, I v1, I w1) and the output currents (I u2, I v2, I w2) are combined, creating new three-phase output current, and wherein The generated output currents are input to the corresponding AC grid. Here, the power converter is controlled such that the sum of the three-phase output currents is zero.
The circulating
For example, the circulating
In summary, the power conversion apparatus of the present embodiment additionally includes a circulating
In the conventional power conversion apparatus, there is only an inverter control unit for controlling the inverter. The circulation current problem does not occur when the power converter includes only one inverter, but when two or more inverters are connected in parallel, a circulating current may occur between the inverters.
However, the inverter control unit can not control the circulation current. When the circulating current is generated, the total energy conversion efficiency of the power converter may be reduced and the quality of the output current may be deteriorated.
On the other hand, the power conversion apparatus of the present embodiment may further include a circulating current control unit to suppress the circulating current between the inverters connected in parallel. As a result, since the circulating current is not generated, the total energy conversion efficiency of the power conversion apparatus can be improved and the quality of the output current can be improved.
In the above description, only the
Further, in the circuit in which three or more inverters are connected in parallel, for example, operation controllers for controlling operations of the remaining inverters other than the operation controller for controlling the operation of the first inverter each include a circulating current controller . That is, when there are N inverters, there are (N-1) circulating current controllers.
FIG. 3 is a circuit diagram showing a detailed structure of the power conversion apparatus of FIG. 2, and FIG. 4 is a diagram illustrating an operation control unit according to an embodiment of the present invention.
Referring to FIG. 3,
The two
The two
The two
On the other hand, the nodes between the
The two
The two
The two
Hereinafter, the specific structure and operation of the
The second
The circulating
The first axis
Article with a biaxial
The
The anti-windups 418 and 420 are used to solve the problem that
The rotation coordinate inverse
The axis inverse
The space
The final output of the
The summing
The
For example, the
The output of this
Here, the output of the
On the other hand, since the circulating
In summary, the power conversion apparatus of the present embodiment can suppress the circulation current by using the circulation
delete
delete
On the other hand, the components of the above-described embodiment can be easily grasped from a process viewpoint. That is, each component can be identified as a respective process. Further, the process of the above-described embodiment can be easily grasped from the viewpoint of the components of the apparatus.
In addition, the above-described technical features may be implemented in the form of program instructions that can be executed through various computer means and recorded in a computer-readable medium. The computer-readable medium may include program instructions, data files, data structures, and the like, alone or in combination. The program instructions recorded on the medium may be those specially designed and constructed for the embodiments or may be available to those skilled in the art of computer software. Examples of computer-readable media include magnetic media such as hard disks, floppy disks and magnetic tape; optical media such as CD-ROMs and DVDs; magnetic media such as floppy disks; Magneto-optical media, and hardware devices specifically configured to store and execute program instructions such as ROM, RAM, flash memory, and the like. Examples of program instructions include machine language code such as those produced by a compiler, as well as high-level language code that can be executed by a computer using an interpreter or the like. The hardware device may be configured to operate as one or more software modules to perform the operations of the embodiments, and vice versa.
It will be apparent to those skilled in the art that various modifications, additions and substitutions are possible, without departing from the spirit and scope of the invention as defined by the appended claims. Should be regarded as belonging to the following claims.
200:
210: first switching unit 212: second switching unit
220: first operation control section 222: second operation control section
230: first inverter control unit 232: second inverter control unit
234:
Claims (12)
A second inverter connected in parallel with the first inverter, the second inverter including second switches for adjusting three-phase output currents;
A first operation control unit including a first inverter control unit for controlling on / off operations of the first switches;
And a second operation control unit including a second inverter control unit and a circulation current control unit for controlling on / off operation of the second switches and suppressing a circulating current that may be generated between the inverters,
The circulation current control unit includes a sum unit for calculating the value of the circulation current by summing the three-phase output currents of the second inverter, and a compensating operation for suppressing the circulation current according to the output of the summation unit, A compensation controller,
The output of the compensation controller is equally added to the three-phase outputs of the second inverter controller, and the second operation controller adds the output of the circulating current controller to the output of the second inverter controller, Adjusting the duty ratio,
Wherein the compensation controller is any one of a proportional-integral controller, a type 1 proportional-resonant controller, and a type 2 proportional-resonant controller, and wherein the proportional-integral controller, the type 1 proportional-resonant controller and the type 2 proportional- Wherein the function is expressed by the following equation.
Here, k p is a proportional constant, k i is an integration constant, ω c is a cutoff frequency, and ω 0 is a frequency of the three-phase output current.
And a code converter for converting the sign of the output of the summation unit,
Wherein the compensation controller outputs a compensation value for suppressing a circulation current according to an output of the sign converter.
An inverter control unit for controlling operations of the switches included in the second inverter; And
And a compensation unit for compensating an output of the inverter control unit to adjust a duty ratio of the switches,
Wherein the compensation unit comprises: a summing unit for calculating a value of a circulation current by summing the three-phase output currents of the second inverter; and a compensation controller for performing a compensation operation for suppressing a circulation current according to an output of the summing unit, Lt; / RTI >
The output of the compensation controller is equally summed with the three-phase outputs of the inverter controller,
Wherein the compensation unit is any one of a proportional-integral controller, a type 1 proportional-resonant controller, and a type 2 proportional-resonant controller, and the transfer function of the proportional-integral controller, the type 1 proportional- Is expressed by the following equation.
Here, k p is a proportional constant, k i is an integration constant, ω c is a cutoff frequency, and ω 0 is a frequency of the three-phase output current.
Checking the value of the circulating current through the sum of the detected output currents; And
And suppressing the circulation current by compensating a control value for controlling the switches in the second inverter according to the determined value of the circulation current,
The step of suppressing the circulation current may include: outputting a control value for complementarily operating the switches included in the second inverter; Outputting a compensation value according to the determined value of the circulating current; And outputting control signals for controlling the switches by summing the output compensation value with the output control value,
Wherein the compensation controller outputs a compensation value using one of a proportional-integral controller, a type 1 proportional-resonance controller and a type 2 proportional-resonance controller, wherein the proportional-integral controller, the type 1 proportional-resonance controller and the transfer function of the type 2 proportional-resonance controller is expressed by the following equation.
Where k p is a proportional constant, k i is an integral constant, ω c is a cutoff frequency, and ω 0 is the frequency of the detected output currents, respectively.
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KR1020160017100A KR101789913B1 (en) | 2016-02-15 | 2016-02-15 | Power conversion device for preventing a circulating current and method of driving the same |
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Cited By (1)
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KR20240048042A (en) | 2022-10-04 | 2024-04-15 | (주)베러셀 | Average current value transmitter of large-capacity parallel power converter |
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KR102134074B1 (en) * | 2018-11-05 | 2020-07-14 | 한양대학교 산학협력단 | Power conversion device for preventing a circulating current and control method thereof |
KR102239429B1 (en) * | 2019-01-29 | 2021-04-12 | 한양대학교 산학협력단 | Power converter and method of reducing circulating current |
Citations (1)
Publication number | Priority date | Publication date | Assignee | Title |
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KR100301307B1 (en) * | 1998-05-08 | 2001-10-27 | 이건수 | Circular current control system of parallel invertor |
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Publication number | Priority date | Publication date | Assignee | Title |
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KR100301307B1 (en) * | 1998-05-08 | 2001-10-27 | 이건수 | Circular current control system of parallel invertor |
Cited By (1)
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KR20240048042A (en) | 2022-10-04 | 2024-04-15 | (주)베러셀 | Average current value transmitter of large-capacity parallel power converter |
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